Process for preparing substituted dialkyl nitrolalkyl phosphates and thiophosphates



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PROCESS FOR PREPARING SUBSTITUTED DI- ALKYL NITROALKYL PHOSPHATES AND THIOPHOSPHATES No Drawing. Filed July 23, 1958, Ser. No. 750,320

2 Claims. (Cl. 260294.8)

This invention relates to new organophosphorus compounds and to their method of preparation. In a specific aspect this invention relates to the preparation of new dialkyl nitroalkyl phosphates and thiophosphates from dialkyl or substituted dialkyl phosphates or phosphorothiolothionates and to the products of this process.

organophosphorus compounds have evidenced marked utility and importance in many fields. For example, they have been employed as insecticides, fungicides, pesticides and in related uses. Consequently, it is of considerable importance to discover new and useful organophosphorus compounds and to have a new process for the production of organophosphorus compounds. Therefore, it is an object of this invention to provide new and useful organophosphorus compounds. It is another object of this invention to provide a novel method for preparing the new and useful organophosphorus compounds. It is still another object of this invention to provide new and valuable insecticides that can be used in various insecticidal compositions.

In accordance with this invention it has been found that new organophosphorus compounds, useful as insecticides, can be prepared by reacting dialkyl or substituted dialkyl phosphates or phosphorothiolothionates with certain nitro-olefins or alkoxynitroethylenes. The new products of this invention have the structural formula:

wherein R and R are selected from the group consisting of alkyl, haloalkyl (chloroethyl, chloropropyl, trichloroethyl, and the like) and alkoxyalkyl (methoxymethyl, methoxyethyl, methoxypropyl, and the like), R is selccted from the group consisting of hydrogen and alkyl, R is selected from the group consisting of phenyl, alkoxy, alkylthio, halophenyl, nitrophenyl, thienyl, pyridyl and furyl, and X is either sulfur or oxygen. In the definition of R R R and R the alkyl and alkoxy radicals are of the lower molecular weight type and they contain 1 to 4 carbon atoms.

The compounds of this invention can be prepared by using an organophosphorus compound having the following structural formula:

wherein R and R are as defined above. This organophosphorus compound is reacted with a nitroolefin having the structural formula:

C=CHNO2 wherein R and R are as defined above. Alternatively atent O the compounds of this invention can be prepared by reacting a compound having the following structural formula:

with a compound having the formula:

R3 OH 3OHzNO2 wherein R R R and R are as defined above.

The dialkyl or substituted dialkyl phosphorothiolothionates used in preparing the compounds of this invention can 'be readily prepared by the reaction of 4 moles of the appropriate alcohol with one mole of phosphorus pentasulfide. The nitroolefins used in practicing this invention can be prepared by the condensation of the appropriate aldehyde with a nitroalkane such as nitromethane, nitroethane, nitropropane and the like. The alkoxynitroethylenes can be prepared from orthoesters and nitromethane by the appropriate modification of the procedure described in Ber. 55, 3441 (1922).

In the practice of this invention we prefer to add one of the reactants gradually to a reactor containing the other reactant. For example, the nitroolefin can be added gradually to a reactor containing the phosphorus compound. Alternatively however, the reverse procedure of addition of reactants can be used but in those instances where polymerization of the nitroolefin is an appreciable side reaction it is preferred to add the stabilized vinyl compound to the phosphorus compound. Normally it is desirable to employ a reactor provided with adequate means of agitation and, since the reaction is quite exothermic, it is also desirable to employ a reactor that is provided with adequate cooling means.

The operable temperature range for the reaction is generally from ,-25 to 150 C. and the preferred temperature range is from 25 to C. However, it will be realized that in some instances temperatures outside this range can be employed. The reaction time usually varies from /2 to 8 hours, but longerand shorter reaction periods are sometimes used. Normally it is unnecessary to employ a catalyst for the reaction'since the dialkylphosphorothiolothionate will react with these unsaturated compounds in the absence of a catalyst. Ifit is considered desirable to employ a catalyst, there are certain catalysts that can be used, for example, the tertiary amines, such as triethyl amine, and the like.

Ordinarily, it is not necessary to employ a solvent for the reaction but in some instances solvents are desirable. Among the solvents that can be used are normally liquid aliphatic and aromatic hydrocarbons such as pentane, heptane, octane, benzene, toluene, the xylenes and the like, chlorinated derivatives of the above-mentioned hydrocarbons as wellas the common ether and ester solvents. It is preferable to carry out the reaction using equimolar quantities of the reactants. However, it is within the scope of our invention to use any molar ratio of reactants.

.In the reaction involving the nitroalcohols the phosphorochloridate or phosphorochloridothionate and the nitroalcohol are generally reacted in organic solvents, for example, the solvents set forth above using a tertiary amine such' as triethyl amine to absorb the hydrogen chloride formed' during the reaction. These reactions can also be carried out in an aqueous system using inorganic bases such as sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate and the like to neutralize the liberated hydrogen chloride.

The following examples are illustrative of-the com- Patented Dec. 13, 1960 pounds within the scope of this invention, their method of preparation and their utility as insecticides.

Example J.0,0-diethyl S-[a-(nitromethyl)benzyl] phosphorothiolothionate Q-on-onmm s 002115 ll/ ooam This compound was prepared according to the procedure given in Example 1 from fl-nitrostyrene (0.1 mole) and O-ethyl, O-propyl phosphorothiolothionate.

Example 3.-0,O-di-(2,2,2 trichl0r0ethyl) S-(I-ethoxyl-methyl-Z-nitroethyl) phosphorothiolothionate CHa-c-CHaNO2 SP(S)(OCHzCCla)z This compound was prepared according to the procedure of Example 1 from 1-nitro-2-ethoxy-1-propene (0.1 mole) and 0,0-di-2,2,2-trichloroethyl phosphorothiolothionate (0.1 mole).

Example 4'.-Oethyl, O-propyl S[I-(ethylthi0)-2- nitroethyl] phosphorothiolothionate CzHaS-CH-CHtNOz s P (s) (0 C2115) (0 03111) This compound was obtained from the addition of.0.1 mole of 1-nitro-2-ethylthioethylene to O-ethyl, O-propyl phosphorothiolothionate (0.1 mole) inbenzene according to the procedure of Example 1.

Example 5.0-ethyl, O-propyl S-(-1 -ethoxy-2-nitr0- ethyl) phosphorothiolothionate CzH5OCH-OH2NO2 SP(S)(OCH5)(OO@H1) This compound was obtained by the addition of l-nitro- 2-ethoxyethylene (0.1 mole) to O-ethyl, O-propyl phosphorothiolothionate (0.1 mole) in hexane solvent.

Example 6.0,0-di(2,2,2-trichl0r0ethyl) S-[a-(nitromethyl)-4-chlorobenzyl] phosphorothiolothionate m-Q-on-cnmm This compound was obtained by the addition of 1-(pchlorophenyl)-2-nitroethylene (0.1 mole) to 0,0-bis- (2,2,24richloroethyl) phosphorothiolothionate (0.1 mole) in benzene solvent.

Example 7.-0,0-di-(Z-methoxyethyl) S-[a-(nitromethyl)-3-nitr0benzyl] phosphorothiolathionate I s? s OCH 11 This compound was prepared by the addition of 1-(m- 4 nitrophenyl)-2-nitroethylene (0.1 mole) to 0,0-bis(2- methoxyethyl) phosphorothiolothionate in benzene solvent.

Example 8.-0,0-diethyl S-[a-(nitromethyl)-2-chl0r0- benzyl] phosphorothiolothionate This compound was obtained from l-(o-chlorophenyD- 2-nitroethy1ene (0.1 mole) and 0,0-diethyl phosphorothiolothionate (0.1 mole) in benzene solvent.

Example 9..0,0-diethyl S- [2-11 itro-I (Z-thienyl ethyl phosphorothiolothionate S P (S) 02115): This compound was prepared from 1-(2-thienyl)-2-nitroethylene and 0,0-diethyl phosphorothiolothionate in benzene solvent. Example 10.--0,0-diethyl S-[2-nitr0-1-(3-pyridyl) ethyl] phosphorothiolothionate CHOH:NO

SP(S)(OCaHa)a N This compound was prepared by the addition of 0.1 mole of 1-(3-pyridyl)-2-nitroethylene and 0,0-diethyl phosphorothiolothionate in benzene solvent.

Example 11.0,0-diethyl S- [1-(2 furyl)-2- nitroethyl] phosphorothiolothionate SP(S)(OC2H5)2 This compound was prepared by the reaction of 1-(2- furyD-Z-nitroethyIene (0.1 mole) with 0,0-diethyl phosphorothiolothionate.

Example 12.Diethyl Z-nitro-I-(2-pyridyl)ethyl phosphorothionate Example I 3.-Diethyl 2-nitro-1-(4-pyridyl) ethyl phosphate NozoHzono P (o) (0 0mm This compound was prepared from 0.1 mole of diethyl phosphorochloridate and 0.1 mole of a-nitromethyl-4- pyridinemethanol according to the procedure of Example 14 using toluene as the solvent and dimethylaniline as the base to absorb the liberated HCl.

Example 14.-Use of compounds as insecticides Tests against mites were carried out in the following manner. Acetone solutions containing 1% of the candidate compounds were prepared and diluted with water to give solutions of the desired concentration for testing. Two heavily infested bean leaves containing adult twospotted mites (Tetranychus bimaculatus Harvey) were carefully dipped in the above solutions and dried in a gentle air stream. The leaves were then placed on damp paper toweling in Petri dishes and observed after 24 hours for mortality among the adult mites.

It should be noted that tests using acetone-water solutions (containing none of the toxicant) kill none of the mites.

TABLE 1 Concentration of Toxicant in p.p.m.

Toxlcant 1. 0,0-D1ethy1 s-[a-(nitromethyl) benzyl] phosphorothiolothionate (Ex. 1)

2. O-Ethyl, O-propyI-S(a-lnitromethyl) benzyl] phosphorothlolothionate (Ex. 2)

3. 0,0-Dl-(2,2,2-tr1ch1or0ethyl) S-(l-ethoxy-lith3y)1-2-nitroethy1) phosphorothiolothlonate 4. 0,0-Dlethyl S-[2-n1tro-1-(2- hlenyDethyl] phosphorothiolothionate (Ex. 9)

TABLE II LD85 in p.p.m.

Toxieant Insect mites mite eggs..-- aphids mites.

0,0-Dlethyl s-[u-(nltromethyl) benzyl] phosphorothiolothlonate. 0,0-Diethyl S-[1-(2-turyl)-2-n1troethy1] phosphorothiolothionate.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. The method for preparing phosphorus-containing compounds which comprises reacting an organophosphorus compound having the structural formula:

Rho wherein R and R are selected from the group consisting of alkyl, haloalkyl, and alkoxyalkyl and X is selected from the group consisting of oxygen and sulfur with a nitroalcohol having the structural formula:

wherein R is selected from the group consisting of hydrogen and alkyl and R is selected from the group consisting of phenyl, alkoxy, alkylthio, halophenyl, nitrophenyl, thienyl, pyridyl and furyl, said alkyl and alkoxy radicals containing from 1-4 carbon atoms at a temperature within the range of 25 to C. and for a period of time within the range of /z-8 hours.

2. The method for producing diethyl 2-nitro-1-(2-pyridyl)ethyl phosphorothionate which comprises reacting diethyl phosphorochloridothionate with a-nitromethyl-Z- pyridinemethanol at a temperature within the range of --25 to 150 C. and for a period of time within the range of 0.5 to 8 hours.

References Cited in the file of this patent UNITED STATES PATENTS 2,177,757 Vanderbilt Oct. 31, 1939 2,526,179 West Oct. 17, 1950 2,706,194 Morris et al. Apr. 12, 1955 2,724,719 Markley et a1. Nov. 22, 1955 2,789,124 Gilbert et al. Apr. 16, 1957 2,862,019 Schrader Nov. 25, 1958 2,889,330 Baker June 2, 1959 OTHER REFERENCES Frear et al.: J. of Economic Entomology, vol. 40, pp. 736741 (1947).

Norman et al.: J. Am. Chem. Soc., vol. 74, pp. 161- 163 (1952).

MelNikov et al.: Chem. Abstracts, vol. 48, cols. 556- 557 (1954).

Gar et al.: Chem. Abstracts, vol. 48, cols. 6639-6640 (1954). 

1. THE METHOD FOR PREPARING PHOSPHORUS-CONTAINING COMPOUNDS WHICH COMPRISES REACTING AN ORGANOPHOSPHORUS COMPOUND HAVING THE STRUCTURAL FORMULA: 